In existing wheeled land vehicles, wheels are supported for rotation by a half shaft which rotates about its axis to provide torque to the wheel. For ease of assembly, repair itself, the wheel typically includes a mounting bracket, and the half shaft is connected to the mounting bracket of the wheel has an internal spline which mates with an external spline on the half shaft. While the mating spline may involve a single longitudinally extending ridge in a corresponding recess, more commonly there are numerous longitudinally extending ridges that mate into corresponding recesses. On the half shaft, the spline is located slightly inward from the end of the half shaft, and the end of the half shaft includes a standard male thread similar to a bolt. The mounting bracket of the wheel is then secured to its half shaft by a threaded locking nut rotationally secured onto the male thread of the half shaft. When assembled; the drive force of the half shaft is transmitted to the wheel by the internal spline and the external spline, enabling the wheel to work as intended.
In order to enable assembly, there must be some fit clearance between the external and internal splines. At the same time, during use it is desired to minimize any play between the wheel mounting bracket and its half shaft. Manufacturing tolerance on the two mating splines are accordingly quite tight and precise, increasing cost to the manufacturing process.
Even with highly accurate manufacturing and tight tolerances, the clearance required for assembly can result in slight movement between the internal spline and the external spline at times of high acceleration or deceleration or when the vehicle is impacted. As a result of this slight back-and-forth movement of the internal spline and the external spline, there are times when the locking nut may slowly loosen. Eventually, the loosened locking nut could lead to unsafe conditions. Ways to prevent loosening of the locking nut are needed, while still permitting ease of initial assembly and repair when needed, and without adding significant cost to the vehicle.